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tater

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Everything posted by tater

  1. It's LESS expensive in dv to lunar orbit—but the orbit is high altitude. They get some benefit by it being eccentric, so it descends closer to the surface at the poles, but from a dv standpoint that doesn't help if the goal is the surface. NRHO is because that is what Orion can do. That's why SLS missions to the actual interesting part of cislunar space—the lunar surface—are so complicated. Apollo sent the CSM-LM to LLO, so the LM needed 2km/s on the descent stage and 2 km/s on the much smaller ascent stage. SLS can send the CSM to NRHO, and then the lander needs 2.75 km/s to the surface, and 2.75 km/s back (maybe split between ascent and descent, maybe 1 vehicle like SS or Dynetics). This results in a substantially larger lander, as the total dv is 5.5 km/s, vs 2 km/s—and since SLS cannot comanifest such a lander, the lander also needs to put itself in NRHO, so it really needs 5.95 km/s—and even if staged, 3.2 km/s of that is with the full lander stack (so most costly propellant wise).
  2. Hires version of the vid posted earlier: Wonder if BO will change their ad copy claiming the largest windows to have flown in space? I suppose they can claim the largest window area of any capsule (sum of windows).
  3. It's that the LOI burn is only 450 m/s. Orion's target orbit is dictated by the low dv of the SM.
  4. @JoeSchmuckatelli I agree on the specs looking great at first glance. I honestly paid little attention early in the SLS program, but a friend of mine who used to write for arstechnica (specifically space reporting) did follow it, and filled me in that it was a "rocket to nowhere." He was actually OK with ARM as a mission, since it was getting made anyway, might as well be used. Anyway, it was only when I started actually running the numbers I realized how unfit for purpose it was. I think it could have been designed in such a way that it's still "SLS," still for BLEO, still uses the Shuttle-adjacent parts (read: contractors), and is still incredibly expensive, and built in all 50 States—but can actually accomplish cool missions. I'd be all-in for it if it could do something cool. They need to either dump Orion, and make a lighter capsule, or beef up SLS well past Block 2 so it can fly with Orion, and the min sortie lander (which I think is ~35t for a RT from NRHO to the surface).
  5. And when you get there you have to eat your fellow passengers to survive.
  6. Tell him to show his work. Presumably there is some NASA link that provides those capabilities. This NASA doc says 22.7t—but it is from Constellation. https://www.nasa.gov/pdf/166914main_FS_Orion508c.pdf This NASA link which is from 2014 says otherwise: https://www.nasa.gov/sites/default/files/fs-2014-08-004-jsc-orion_quickfacts-web.pdf Injected (TLI) mass: 58,467 lbs, which is 26, 520 kg. See, this is the problem—it didn't. I like dumping on the insane cost, etc, but frankly the cost doesn't matter, I get it, that's how the sausage is made. What matters is the capability, and it's just not there, and will never be there. If the purpose was BLEO human spaceflight missions—not singleton capsule flights, but complete missions, like landing on the Moon, or sending humans to Mars, then SLS not only can't do the job by itself, it never can. The cost starts to actually matter, too, when literally any mission requires multiple SLS launches a few weeks apart. Knowing Orion was to be part of the system, TLI capability needed to be ~65t. That's the math. They say, "Hey, we need a "jack of all trades" BLEO crew launch vehicle." Then someone asks, "What are possible missions?" Answer? "Landing on the Moon, building a space station around the moon... building a Mars vehicle in LEO, stuff like that! Oh, and we have a crew capsule capable of Earth return from the Moon or Mars already, Orion!" "Cool, so we need to be able to do those missions, and we need any extra capacity to be in addition to that 26.5t. (scribbles)... so for lunar surface missions we need the thing to throw at least 60, maybe 65t to TLI. Cool, that's doable." The trouble is they set the lift capability without bothering to check if it could accomplish anything first.
  7. We think alike, I did the same thing in the Artemis thread yesterday:
  8. I would agree with this except that SLS lacks capacity. It's for BLEO, yet it can't do BLEO missions, at least not saddled with Orion (which was intentionally made so massive commercial launches could not launch it (ULA at the time, that was Ares era). SLS B1B can do ~37t to TLI? SLS B2 can do ~45 to TLI? Orion CSM is 26.5t and has ~1200 m/s dv. That leaves 17.5t of additional vehicle that can go with Orion. If Orion had more like 2800 m/s of dv, then they could stick an Apollo LM on there (modernized, and lighter (?), with better computers, etc). But Orion can't even do LLO alone, much less pushing a LM. So we have a rocket that cannot do anything useful at all. If Orion was Apollo CM sized, then all the things are possible, and heck, the capsule with a small SM could be used for ISS, too. But Orion is a pig, so...
  9. This is the question that should have been asked before finalizing the design. NASA would not have any more money, SLS was paid for, minus SLS that money does not exist. As for Falcons, if the goal was humans to the lunar surface, F9/FH is not ideal, either.
  10. The whole SLS debacle is just nuts. From the start, the entire point of ICPS was to get the thing tested quickly (end of 2016, lol) before launching the thing "all up" with EUS. So they built the MLS for that single launch at a cost of ~$1B. All this for a program using Shuttle tech to "save money." Like the OMS engines... throw a few away (OK, those are paid for at least), then buy new ones for at least an order of magnitude higher cost than they should be. They are more than 10X the cost of Be-4—very different, but also far more complex. I could compare to Raptor, but then it gets almost comical.
  11. There was supposed to be a exploration director added (basically what this is), I think it's less about the actual change, and more about the way it looks externally. That may be the point. Minus the whole BO lawsuit, etc, I think it's less of a thing, but it was not done in the best possible way—if that makes any sense.
  12. Gottagetthereitis is always gonna be a problem. In the case of people who shouldn’t be on Everest being on Everest, the thing is they are often not really rich enough. If you save for a once in a lifetime thing and they say, “dude, you need to go down, this isn’t happening for you this year” you’d feel a lot of internal pressure to summit anyway. If you could do it again next year, money/time is no issue? Sure, better luck next time. If it gets to the point where there is “go” pressure on the provider I think it’s a problem.
  13. Expressing your displeasure by saying you'll never fly this airline again is entirely reasonable, that's exactly how a person expresses such displeasure with a business—by not patronizing them in future. Jerry Springer style conflict, OTOH... yeah, I don't see that as terribly likely.
  14. Note that even if they could comanifest more than 11t to TLI—Orion could not deal with that. The dv of the SM is small enough that with an 11t module, it can take it to NRHO, and still come home, but some amount above 11t, and it lacks the dv to return since while the 450 m/s burn from TLI to NRHO is tiny, it will use more props to do that with cargo. If they used the extra TLI throw to make a decent SM (using the same engine, they'd likely want 2 though), it looks like Orion could fly to and from LLO directly (just).
  15. Block 1 B has 2 purposes. Most importantly, it allows a single TLI burn. That's the reason it exists—the Block 1 ICPS was never supposed to be used with people because it is so weak and requires multiple burns. That it can haul some light module is fine, but given the program, any such module likely costs some insane amount of money. As to taking extra cargo... it sort of depends. Adding modules every single trip increases Gateway's size, which might not actually be desirable, more modules, more radiators, more solar, more ECLSS, etc.
  16. I mean Block 1B is mass limited to TLI—10-11t of comanifested cargo is not enough mass to do anything useful. I never bothered to see if the volume was a problem—because there wasn't enough throw anyway. If it could take 30t, then it would be worth looking to see if you could fit a 30t lander in there.
  17. There is a space above the EUS and below Orion for comanifesting items to TLI. The trouble is the mass limits. It's enough form a module for Gateway, maybe a docking port, or airlock. That's it.
  18. Be-4 engines are expensive and they are still <$7M. Why are we trading the SM for rides for ESA again?
  19. Pure insanity. The WHOLE POINT was to reuse Shuttle tech. This is the Shuttle OMS engine—which is the AJ-10, since Atlas and Thor. Apollo SM. This is INSANELY STUPID. Sorry for yelling, but there is ZERO excuse for a single tiny engine from the 1960s to cost more than buying a F9 launch—a Vulcan launch is supposed to be ~$80M. 1 engine.
  20. Engines for 8 missions for $600M. That's $75M per engine (1 per SM). How is it that the "European" service module results in the US taxpayer buying the engines, exactly? Then we buy them for way, way too much money. The whole SM should cost $75M, not 1 engine.
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